test: move pummel/test-tls-fragmentation to benchmark/

Said test takes over 90 seconds on my Core 2 Duo which is too long, even for
the pummel tests.

diff --git a/test/pummel/test-tls-fragmentation.js b/benchmark/tls-fragmentation.js
similarity index 100%
rename from test/pummel/test-tls-fragmentation.js
rename to benchmark/tls-fragmentation.js